1. Field of the Invention
This invention provides new composites, which can be used in the preparation of fabrics for protective clothing, filters, structural preforms, and membranes. These composites exhibit a wide variety of functional characteristics.
2. Description of the Prior Art
Synthetic fabrics, both woven and non-woven, are well known and have been used in countless applications for some time. Many of these fabrics may be characterized as composites in that they are comprised of two or more distinctively different materials that are bound together in some manner to provide a single material whose properties differ from that of either of its constituent elements. Typical applications for these fabrics or composites include, but are not limited to, the fabrication of protective clothing, filters, screens, protective shields, and numerous decorative items.
Of particular interest in this art and to the present inventors is the use of fabrics and/or composites in the fabrication of chemically absorptive clothing. Currently, protective clothing for certain chemical environments utilize polyurethane foam laminated to a tricot-knit nylon cloth and then impregnated with activated charcoal. A latex compound is used to bind the charcoal to the foam, and mechanical strength is provided by the nylon. There are, however, several drawbacks to this prior art material which originate with the foam portion of the laminate. First, the processing required to fabricate the laminate is expensive and complicated. Second, some of the properties of the final material do not fit the above application. The foam is flammable and it has low thermal conductivity resulting in large heat loads on the wearer. The low permeability of foam to water vapor accentuates the latter problem. Third, because of reversion of the polyurethane, the material has limited shelf life. Finally, the necessity of using a latex compound to bind the charcoal to the foam, or some other resin as a binder for the solid particles, further lessens the utility of prior art composites having solid particles. Resin or latex matrices are generally impermeable to moisture as well as to air and tend to coat the surfaces of the active particles as well as binding them to the fabric.
Consequently, there is still a need to provide materials of the type generally described above of equal or better chemical absorptivity than the current materials while achieving higher moisture permeability, lower heat loads, lighter weight, and greatly extended shelf life. It is the fulfillment of this need to which the present invention is directed. However, the techniques developed are suitable for many other applications and are not limited to absorbent protective clothing.